The most common and most likely answer to this crossword clue is the 4 plus 6 letter word DEAD RINGER
D
E
A
D
R
I
N
G
E
R
More clues leading to the result DEAD RINGER
- Exact replica / phone cut off, perhaps?
- Exhausted campanologist’s double?
- Lookalike‘s campanologist no longer with us
- Quasimodo’s identical twin?
- Band occupying number one looks very much like another
- It looks like the campanologist is late
- Deceased bellman’s double
- Late caller gets double
- Late caller, one’s same as another
- It looks like one campanologist is late
Buddy explains!

The straight part
We know that "double" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case double = dead ringer.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.